It's just the way that SQL Server deals with Monetary data. It's always got four trailing spaces for decimals, and the decimal symbol (".") is interpreted as being the symbol to indicate that you're dealing with the decimal part of the Money value, while the comma (",") is treated as being part of the non-decimal part.

EG: 1,000 is the same as 1000, while 1.000 is the same as 1, and 1,000.1 is the same as 1000.1